In order to solve environmental pollution problems including global warming due to fossil fuel usage and an energy shortage phenomenon due to fossil fuel depletion, various alternative energy are being researched. As one of the alternative energy, a study on hydrogen is being accelerated.
The hydrogen energy may have an advantage solving all the above-described two problems and be obtained from water abundantly distributed in the earth. Also, the hydrogen energy may overcome the finitude of the conventional fossil fuel as an energy source capable of being recycled into the water when the use thereof is completed. Furthermore, the hydrogen may not generate pollutants except for an extremely small amount of NOx. Thus, the development of the hydrogen energy is being accelerated in recent years to solve the energy resource depletion and the environmental pollution problems at the same time. Accordingly, the hydrogen energy is expected to be widely used.
However, the hydrogen gas may have a risk of explosion when the hydrogen gas of 4% to 75% or more leaks into the atmosphere. Thus, the hydrogen gas is hard to be applied as the hydrogen energy source in hydrogen fuel for home and a hydrogen fuel cell vehicle unless an accurate and stable management is secured. Thus, needs for hydrogen sensors, which are capable of early detecting the leakage of hydrogen, are being on the rise.
Sensors using catalyzed combustion or a heating wire and semiconductor sensors using silicon dioxide (SiO2), aluminum nitride (AlN), and metal oxide (nitride) are being developed as the hydrogen sensors. However, the above-described sensors have not only large sizes and complex structures, but also have a high cost.